1. Field of the Invention
The present invention relates to a seal ring which is incorporated in, for example, a rolling bearing and relates to a sealing apparatus so-called a pack seal.
The present invention, more particularly, relates to a seal ring into which a rotation detecting sensor is incorporated, a sealing apparatus into which a rotation detecting apparatus composed of the above sensor and a pulsar ring whose rotation is detected by the sensor, and a bearing apparatus having them.
2. Description of the Related Art
Both a magnetic sensor and a pulsar ring provided with N poles and S poles alternatively in a peripheral direction are incorporated as a rotation detecting device into, for example, a bearing apparatus for an axle of an automobile, and they are used for detecting a wheel speed when anti-locking brake control is made.
The present inventors suggest a structure that such a rotation detecting device is integral with a sealing apparatus called as a pack seal.
The seal pack of this suggestion has an outer diameter side seal ring fixed to an inner periphery of an outer ring of a rolling bearing, and an inner diameter side seal ring fixed to an outer periphery of an inner ring.
The magnetic sensor is attached to an inner diameter side of the outer diameter side seal ring. The pulsar ring is attached to an outer diameter side of the inner diameter side seal ring so as to face the magnetic sensor in a radial direction.
In this case, the magnetic sensor is attached to an inner periphery of an annular body of the outer diameter side seal ring by a mold using a resin material. The resin material is formed integrally with or bonded to the annular body of the outer diameter side seal ring so as to become a outer case which covers a periphery of the sensor.
Such a structure is provided because the annular body of the outer diameter side seal ring is press-fitted into an inner peripheral surface of an outer ring or the like so that the outer diameter side seal ring is attached firmly to the outer ring.
However, in the case of the structure that the magnetic sensor is attached to the inner periphery of the annular body of the outer diameter side seal ring by the mold, since a difference in coefficient of linear expansion between the annular body of the outer diameter side seal ring and the outer case is large, after the outer case is formed, it contracts. As a result, a gap is easily generated on a boundary surface between the inner periphery of the annular body of the outer diameter side seal ring and the outer case.
When such a gap is generated, water which splashes on the seal ring from the outside easily penetrates from the gap into the bearing, and this might cause deterioration of the bearing performance such that lubricant inside the bearing is deteriorated.
Therefore, a main object of the present invention is to provide a seal ring in which a gap is hardly generated on a boundary surface between an annular body of the seal ring and an outer case so that high sealing performance is provided.
Other objects, characteristics and advantages of the present invention will become clear from the following description.
A seal ring according to the present invention is attached to an inner peripheral surface of a fixed outside member, and forms a sealing section on an outer peripheral surface of an inside member to be inserted through the outside member inwardly and rotatably. The seal ring has an annular body with a substantially cylindrical shape, and a sensor member is provided to an outer peripheral side of the annular body, and a resin-made outer case, which is fitted into said outside member in states that the outer case covers the sensor member and has a predetermined interference for the outside member, is provided by insert-forming.
In the case of the present invention, since the outer case formed on the outer periphery of the annular body is formed integrally or bonded to the outer periphery of the annular body in states that its contraction towards an radially inward direction and the outer case press-contacts therewith, a gap is hardly generated on a boundary surface between the annular body and the outer case. Therefore, a seal ring having high sealing performance can be provided.
The invention is preferably constituted so that the sensor member is arranged so as not to contact with the inner peripheral surface of the outside member and so as to substantially contact with the outer peripheral surface of the annular body.
In this case, since resin is interposed between the outside member and the sensor member, even if a gap is generated on a surface between the outside member and the outer case and water penetrates from the gap, the water does not contact with the sensor member. As a result, electrically short-circuit of the sensor member can be prevented securely.
The present invention is preferably constituted so that the sensor member is arranged so as not to substantially contact with the outer peripheral surface of the annular body.
The present invention is preferably constituted so that the sensor member is arranged so as not to substantially contact with the inner peripheral surface of the outside member.
In these cases, since resin is interposed between the annular body and the sensor member, even if a gap is generated on a boundary surface between the outside member and the outer case and water penetrates from the gap, the water does not contact with the sensor member. As a result, electrically short-circuit of the sensor member can be prevented securely.
The present invention is preferably constituted so that an elastic lip, which is brought into contact with the outer peripheral surface of the inside member or a member attached to the outer peripheral surface so as to form a contact sealing section, is provided to the annular body.
In this case, since the contact sealing section is formed by the elastic lip, the sealing performance of the seal ring is heightened.
The present invention is preferably constituted so that a harness for covering signal lines connected with the sensor member is embedded into the outer case.
With this structure, even if a slight gap is generated on a boundary surface between the harness and the resin-made outer case and the water penetrates through the gap, the water does not reach a contact portion between the sensor member and the signal lines.
In the case where the harness is not embedded into the resin-made outer case and only the signal lines are embedded, if a slight gap is generated on a boundary surface between a jacket of the signal lines and the resin-made outer case and the water penetrates from the gap, the water goes along the jacket and conductors of the signal lines and reaches the connected portion of the sensor member and the signal lines. As a result, there possibly arises a defect that the sensor member is electrically shorted-circuited.
On the contrary, it is preferable that the harness is embedded into the outer case because the above-mentioned defect is prevented securely.